Adjuvant therapy regimens containing hormonal agents such as anastrozole with or without chemotherapy have significantly improved the cure rate for women with early stage breast cancer. However, several negative sequelae are associated with this treatment including cognitive impairment that may lead to a deterioration in quality of life. Our pilot data suggest that cognitive impairment is more severe and affects more cognitive domains in women who receive a hormonal agent as part of their adjuvant therapy regimen compared to women with breast cancer who receive chemotherapy alone or no adjuvant therapy. Cognitive impairments in women with breast cancer who receive anastrozole may include deficits in verbal memory and psychomotor speed. Unfortunately, the study that detailed cognitive impairment with anastrozole use was cross sectional and measured cognitive function with a limited battery an average of 36 months following the initiation of treatment. The aims of this proposed study are: 1) to examine and compare the effect of anastrozole on cognitive function in four cohorts of women (n = 360; 90 per group): a) women with breast cancer who receive chemotherapy plus anastrozole; b) women with breast cancer who receive chemotherapy alone; c) women with breast cancer who receive anastrozole alone; and d) a healthy control group of women matched on age, race and level of education and 2) to develop a characteristic profile of women at risk for cognitive impairment. Secondary aims are to explore: 1) the quality of life of women who receive anastrozole and whether cognitive impairment affects quality of life in this sample; 2) whether anastrozole adherence and changes in hormone levels are mediators of cognitive function; and 3) whether mood, fatigue, treatment related symptoms, and concomitant medications are moderators of cognitive impairment and quality of life. Using a prospective, four-group, repeated measures design, we plan to evaluate cognitive function, quality of life and potential mediators and moderators of cognitive function at three time points; at baseline, prior to the initiation of therapy and six and 12 months post-baseline. Repeated measures analysis, using a mixed modeling approach, logistic regression and latent variable growth curve modeling, will be used to analyze data to address the study aims.